The Mysterious Chemical That Eases Pain, But Also Causes It

By Annalee Newitz

Endocannabinoids are the body's natural form of THC, a chemical in marijuana that can ease pain. Now a new study shows this chemical is a double-edged sword, making people more sensitive to pain too. Could endocannabinoids be used for torture?

Endocannabinoids interact with canniboid receptors the same way the chemical THC in marijuana does. According to a study published this afternoon in Science, the endocannabinoid system is more complex than previously believed. Sometimes a spike in endocannabinoids in the spinal cord releases neurotransmitter chemicals that make people more likely to feel pain.

A release about the article from Science puts it this way:
"Often, in cases of chronic pain, neuron-to-neuron communication is bumped up in a specific area of the spinal cord. Endocannabinoids (which are the body's version of the THC in marijuana) have been thought to suppress this type of pain signaling, but Alejandro Pernía-Andrade and an international team of colleagues now show that the opposite may be true. They found that in rats and mice, painful stimuli can release endocannabinoids in the spinal cord, which act on a group of neuronal receptors called the CB1 receptors. This action reduced the release of key neurotransmitters that shuttle from one neuron to another, with the overall effect of making the neurons more excitable and thereby sensitizing the animals to certain forms of pain, or even to simple touch. In another experiment, on human volunteers, the authors found that the drug rimonabant, which blocks CB1 receptors, decreased pain sensitivity that had been induced in patches of the volunteers' skin."

We're a long way from being able to control this pain/not-pain system, but knowing that it's there means more research into it is inevitable. Already endocannabinoids are a target for a lot of hopeful pharmaceutical companies, who hope to manipulate the substance to treat everything from chronic pain to obesity.

My question is whether this substance could also become the target of military research too, since being able to control whether a person feels pain or not is a classic torture technique. And doing it cleanly, with drugs, could be classified as "humane" under many systems of regulation. Plus, what's a better way to play pharmaceutical good cop/bad cop than to administer a drug that causes pain - then eases it?

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